VOF? How to?

I would appreciate so much if anyone could tell me roughfly how to set up a VOF problem.

For example, I am trying to simulate sea waves in a 2D rectangular domain, which is splitted in 2half rectangles, up and down. The line between each volume fractions I define it as interface. But in fluent I am not able to define both phases and I don't have clear the methodology to follow to make this simulation.